Anti-stalling motor fuel



United States Patent 3,325,260 ANTl-STALLTNG MOTOR FUEL Kenneth L. Billie, Wappingers Falls, Stanley R. Newman, Fishlrill, and Robert Y. Heisler, Wappingers Falls, N.Y.,

assignors to Texaco lino, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 23, 1964, Ser. No. 354,099

7 Claims. (Cl. id-58) This invention relates to a volatile gasoline composition of improved anti-stalling properties containing a light distillate mineral lubricating oil, an oxidate material and Z-methyl-2,4-pentanediol.

The present motor fuel is an improvement over the gasoline disclosed in a commonly assigned application Ser. No. 793,271, filed on Feb. 16, 1959, now U.S. 2,965,458. This commonly assigned patent discloses motor fuel compositions containing 0.2 to 1.0 weight percent of a light distillate mineral lubricating oil and 0.002 to 0.015 weight percent of an oxidate material. These motor fuels are principally characterized by having improved octane values, and improved anti-rust and antiwear properties. The subject invention involves the discovery that the motor fuel compositions of the abovedescribed invention to which has been added a relatively small amount of an alkylene glycol exhibit a remarkable synergistic improvement in their anti-stalling, anti-icing properties.

It has been known heretofore to employ hydroxy compounds such as alcohols and glycols, as anti-stalling components in gasoline. In general, however, these compounds have had to be used in a relatively high concentration, i.e. in the order of 0.5 percent or more, in order to make them effective. The required large amount of a hydroxy compound and particularly a glycol renders their use uneconomical. Moreover, the introduction of such a large amount of this type additive to the fuel gives rise to new fuel problems relating to the stability, storage life and corrosiveness of the motor fuel. For these reasons, the practice of adding large amounts of hydroxy compounds or more particularly of glycols to gasoline has not been widely adopted.

The surprising feature of the present invention is that a very small amount of a glycol, i.e. an amount measured in a few pounds per thousand barrels of gasoline (PTB) or in the order of 0.005 percent, is extremely effective due to a synergistic effect when added to the gasoline of the above-noted patent. It is also surprising that all of the desirable properties of motor fuels of the aforesaid patent are retained in the present gasoline, along with the newly discovered anti-stalling properties.

The outstanding anti-stalling motor fuel of this invention comprises a gasoline containing 0.15 to 1.0 volume percent of a light distillate mineral lubricating oil, 0.002 to 0.015 weight percent of a component which is either an ester-type oxidate derived from deoiled macrocrystalline wax and having a neutralization number between 60 and 100, a saponification number above 170 and a neutralization number to saponification number ratio between 0.25 and 0.5, or an oxidate derived from a paraffinic lubricating oil and having a neutral number between 55 and 80 and a saponification number between 100 and 200, and 0.0005 to 0.08 weight percent of 2- ethyl-2,4-pentanediol.

When internal combustion engines are operated on a gasoline fuel having the desired volatility characteristics for cold weather driving, a stalling problems is encountered during the Warm up period, particularly under cool, humid atmospheric conditions. It has been generally recognized that the cause of repeated engine stalling in cool, humid Weather is the formation of ice in the carburetor. Gasoline evaporating in the carburetor has a sufficient refrigerating effect to condense and freeze the moisture present in the air. Ice particles deposit on the metal surface of the carburetor and partially or completely block the air passage between the carburetor throat and the carburetor throttle valve with resulting stalling, particularly when the engine is idling.

The additive combination of this invention is particularly useful in highly volatile fuels having a Reid vapor pressure above about 9 which are particularly prone to engine stalling due to ice formation under cool weather conditions. Stated another way, the additive of the inven tion is particularly useful in winter gasolines employed in northern portions of the country since they have Reid vapor pressures between about 9 and 13.5 depending on the area in which they are used.

The additive of the invention comprising a light distillate lube oil, an oxidate material of prescribed definition and 2-methyl-2,4-pentanediol is usually employed in premium motor fuels having a high octane rating and comprising a major portion of catalytically cracked base stock. Catalytically reformed gasoline containing a high aromatic content often comprises a substantial portion of a premium fuel of this type. The additive combination is effective both in leaded and non-leaded motor fuels.

The light lube oil component may be a naphthene base distillate, a paraffin base distillate or mixtures thereof, but must have a low carbon residue and an SUS viscosity at 10 F. between 50 and 300. A distillate lube oil fraction of this type is obtained by vacuum distillation of a naphthene base or paraffin base lube oil at approximately 20 to 40 mm. pressure and subsequent acid treatment of the distillate. The lube oil component generally used has an SUS viscosity at F. of about 100. If the light lube oil component of the additive mixture does not have a Conradson carbon content below 0.02 percent and a viscosity within the prescribed range, the resulting gasoline will cause excessive carbonaceous deposits in engines.

The lube oil component constitutes 0.15 to 1.0 volume percent of the gasoline of this invention. The preferred concentration of this component is in the range of 0.3 to 0.8 volume percent with approximately 0.6 volume percent usually being employed.

The ester-type oxidate component of the fuel usually has a neutralization number between 70 and 95, a 'saponification number between 210 and 250 and a neutralization number to saponification number ratio between 0.3 and 0.4. The ester-type wax oxidate component obtained by air oxidation of deoiled macrocrystalline wax is the product which is described in detail in U.S. Patent No. 2,894,970. The ester-type oxidate broadly has a neutralization number of 60 to 100, a saponification number above 170 and a neutralization number to saponification number ratio between 0.25 and 0.5, and preferably between 0.3 and 0.4. The ester-type wax oxidate is obtained by air oxidation of deoiled macrocrystalline wax containing less than 5 percent oil and 20 to 33 carbon atoms per molecule at a temperature between 300 and 350 F. at a pressure below 25 p.s.i.a. and an air velocity of 1.5 to 6 feet per second equivalent to an. air feed rate of 8 to 35 cubic feet of air per pound of wax per hour.

An ester-type oxidate which gives superior results in a motor fuel of the invention has been prepared from a to 127 F. melting point semi-refined paraffin wax separated from a distillate oil of about SAE 20 grade and having about 25 to 30 carbon atoms per molecule. The 125 to 127 F. melting point wax, which contains about 0.2 to 0.4 percent oil is separated from the distillate oil by solvent dewaxing with a solvent, such as a methylethyl ketone-toluene mixture.

The paraflinic oil oxidate of this invention preferably has a neut. number between 60 and 70, a sap. number between 120 and 165, a viscosity less than 100 SUS at 2'10? F., a Lovibond one-half inch cell color rating of less than about 100 and is obtained by air oxidation of a refined paratfin base lubricating oil having a viscosity between 140 and 180 SUS at 100 F., a pour point less than 5 F., a color rating of less than and an aniline point between 2 and 225 F. The parafiinic oil oxidate component obtained by catalytic air oxidation of a refined paraflin base lubricating oil is the product described in detail in application Ser. No. 710,856, filed Jan. 24, 1958, in the names of George B. Kirkwood and John H. Greene. The paraffinic oil oxidate broadly has a neut. number between 55 and 80, a sap. number between about .100 and 200, a viscosity less than 200 Saybolt Universal seconds (SUS) at 210 F., a color rating less than 200 in the Lovibond one-half inch cell, and a pour point less than 30 F.

The oxidate constitutes a very minor portion of the fuel composition of the invention, its concentration falling within the range of 0.002 to 0.015 weight percent of the 'finished gasoline. The usual concentration of the oxidate material is in the neighborhood of 0.004 to 0.008 weight percent of the finished gasoline. Concentrations of oxidate in excess of 0.015 weight percent degrade the properties of the fuel, particularly in the matter of the combustion chamber and intake system deposits.

While the light distillate oil and the oxidate can be separately blended into the motor fuel, it is customary to prepare a mixture of these components. A suitable mixture is prepared by incorporating 0.08 to 0.09 pound of parafiin oil oxidate in a gallon of naphthene base lube oil having an SUS viscosity at 100 F. of about 100. This mixture contains approximately 1.125 percent oxidate. The addition of about 0.5 percent by volume of this mixture in the motor fuel base stock gives a gasoline which also contains approximately 0.0075 weight percent oxidate.

The 2-methyl-2,4-pentanediol constituent of the motor fuel of the invention generally is employed in an amount from about 0.0005 to 0.08 volume percent. The preferred concentration of the 2-methyl-2,4-pentanediol, however, is an amount from about 0.001 to about 0.05 volume percent.

The action of the additive combination as an anti stalling, anti-icing additive was evaluated in a carburetor icing demonstrator apparatus consisting of a vacuum pump equipped so that cooled moisture-saturated air from an ice tower is drawn through a simple glass tube gasoline carburetor. The gasoline sample is placed in a sample bottle and is drawn into the glass carburetor through a hypodermic needle which is usually gauge. Evaporation of the gasoline in the glass tube further cools the cold, moist air with resulting ice formation on the throttle plate. The formation of ice on the throttle plate causes the engine to stall and it has been found that this condition is equivalent to a pressure drop across the throttle plate of about 0.5 inch of mercury and the time to reach this pressure drop is recorded. The vacuum pump is adjusted to 'give a vacuum of 1.8 inches mercury and the test is run until a pressure of 2.3 inches mercury has been reached or has run for 300 seconds. Since with most fuels this pressure drop is reached in 1 to 4 minutes, 300 seconds is the maximum time for a run. A recording of 300 seconds indicates no stall within the test period. Each fuel run is repeated in succession and the average is reported. A leaded Winter grade premium gasoline having a Reid vapor pressure of about 13 gives a stall in about 30-65 seconds in this test. Additives which raise the stalling time to over 150 seconds and preferably over200 seconds are recorded as effective anti-stalling, anti-icing additives.

The base fuel employed to evaluate the effectiveness of the light distillate mineral lubricating oil, oxidate material and alkylene glycol additives as an anti-stalling, anti-icing additive combination was a winter grade premium gasoline having an octane rating of about 101.4 and contained 3 cc. of TEL per gallon. The base fuel which had a 50 percent ASTM distillation point of 214 F. and a Reid vapor pressure of about 13 pounds was ideally suited for testing '4 the effectiveness of the additive combination on the stalling characteristics of the fuel because of its high vapor pressure.

The light distillate mineral lubricating oil used in the tests was a naphthene base oil having an SUS at F. of 100. The oxidate employed was a parafinic oil oxidate derived by catalytic oxidation of a paraffinic oil of SAE 8 grade and having a neut. number of about 70 and a sap. number of about 142.

The following data shows the effectiveness of the additive combination of a light distillate mineral lubricating oil, an oxidate and a glycol as an anti-stalling, anti-icing additive.

CARBURETOR ICING TEST Light Distillate Paratfinie Zmethyl-ZA- Run Mineral Lubri- Oil Oxidate, pentanediol, See. to 0.5 eating Oil, Wt. Percent Vol. Percent in. Hq. AP Vol. Percent 1 None None None 36 2 0. 5 0. 0075 None 87 3 None None 0. 003 40 4 None None 0. 006 40 5 None None 0. 02 48 6 None None 0. 03 58 7 None None 0. 05 99 8. None None 0.10 79 9 O. 5 0. 0075 0. 005 295(+) 10 0. 5 0. 0075 0. ()2 300(+) The motor fuel in Run 1 without any anti-stalling additive produced a stalling condition in 36 seconds. Slight improvements were observed in Run 2 for the fuel containing the lube oil and oxidate and Runs 3 to 8 containing increasing amounts of 2-m-ethyl-2,4-pentanediol, but stalling conditions were encountered in every case in from 40 to 99 seconds. These results are far short of the minimum requirements for an effective anti-stalling gasoline which by this test is a period of no-stalling for at least seconds. The fuels containing all three components, Runs 9 and 10, ran for 295+ and 300+ seconds respectively, the latter Run not producing a stall condition for the entire test period. The anti-stalling characteristics of the motor fuel of the invention represent an outstanding improvement in this important property.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A motor fuel in the gasoline boiling range containing 0.15 to 1.0 volume percent of a light distillate mineral lubricating oil fraction having an SUS Viscosity at 100 F. between 50 and 300*, 0.002. to 0.015 weight percent of an oxidate material selected from the group consisting of an oxidate derived from a deoiled macrocrystalline wax and having a neutralization number between 60 and 100, a saponification number above and a. neutralization number to saponification number ratio between 0.25 and 0.5 and an oxidate derived from a parafiinic lubricating oil and having a neutralization number between 55 and 80, a saponification number between 100 and 200 and a SUS viscosity at 210 P. less than 200, and 0.0005 to 0.08 volume percent of 2-methyl-2,4-pentanediol.

2. A motor fuel according to claim 1 in which said 2-methyl-2,4-pentanediol is employed in an amount from about 0.001 to 0.05 volume percent.

3. A motor fuel according to claim 1 in which the concentration of said oxidate material is between 0.004 and 0.008 weight percent.

4. A motor fuel according to claim 1 in which the concentration of said mineral oil fraction is between 0.3 and 0.8 volume percent and said mineral oil, has an SUS viscosity at 100 F. in the neighborhood of 100 and a Conradson carbon content less than 0.02 percent.

5. A motor fuel according to claim 1 in which said dtl material is an oxidate derived from a parafiinic lubricating oil and having a neut. number between 60 tween 12.0 and 165 and from about 0.001 to 0.05 volume and 70 and a sap. number between 120 and 165. percent of Z-methyl-2,4-pentanedi0l.

6. A motor fuel according to claim 1 containing from about 0.5 to 4 ml. of a tetralkyllead fluid. References Clted 7. A motor fuel in the gasoline boiling range contain- 5 UNITED STATES PATENTS ing 0.3 to 0.8 volume percent of a light distillate mineral 2,701,754 2/1955 Haworth et al. 44--77 lubricating oil fraction having an SUS viscosity at 100 F. 2,965,45 8 12/ 1960 Sawyer et a1. 44-58 of about 100, 0.004 to 0.008 Weight percent of an oxidate derived from a paraffinic lubricating oil and having a DANIEL WYMAN Pnmm'y Examine" neut. number between 6 and 70 and a sap. number be- 10 Y. H. SMITH, Assistant Examiner. 

1. A MOTOR FUEL IN THE GASOLINE BOILING RANGE CONTAINING 0.15 TO 1.0 VOLUME PERCENT OF A LIGHT DISTILLATE MINERAL LUBRICATING OIL FRACTION HAVING AN SUS VISCOSITY AT 100*F. BETWEEN 50 AND 300, 0.002 TO 0.015 WEIGHT PERCENT OF AN OXIDATE MATERIAL SELECTED FROM THE GROUP CONSISTING OF AN OXIDATE DERIVED FROM A DEOILED MACROCYSTALLINE WAX AND HAVING A NEUTRALIZATION NUMBER BETWEEN 60 AND 100, A SAPONIFICATION NUMBER ABOVE 170 AND A NEUTRALIZATION NUMBER TO SAPONIFICATION NUMBER RATIO BETWEEN 0.25 AND 0.5 AND AN OXIDATE DERIVED FROM A PARAFFINIC LUBRICATING OIL AND HAVING A NEUTRALIZATION NUMBER BETWEEN 55 AND 80, A SAPONIFICATION NUMBER BETWEEN 100 AND 200 AND A SUS VISCOSITY AT 210*F. LESS THAN 200, AND 0.0005 TO 0.08 VOLUME PERCENT OF 2-METHYL-2,4-PENTANEDIOL. 